public void generate() {
        Random random = new Random();

        int firstNumber = random.nextInt(31);
        numbers.add(firstNumber);
        maxNumber = firstNumber;
        minNumber = firstNumber;

        int sum = 0;

        while (sum <= 500) {
            int number = random.nextInt(31);
            numbers.add(number);

            if (number > maxNumber) {
                maxNumber = number;
            }

            if (number < minNumber) {
                minNumber = number;
            }

            sum = sum + number;
        }
    }